Tire construction



. 25, 1945. B. E. MENDELSOHN TIRE CONSTRUCTION Filed March 19, 1942 (II/i I 12 men for BER/YARD E. MENDEMOHN 2 70mm?" flfiorney Patented Dec. 25, 1945 UNITED STATES PATENT OFFICE signor, by direct and mesne assignments, of

forty-two and one-half per cent to B. Howard Benson, Boston, Mass., and fifteen per cent to Irving Fisher, New Haven, Conn.

Application March 19, 1942, Serial No. 435,359

Claims.

The present invention relates to an improvement in tire construction, particularly to a construction in which two chambers are formed separated from each other. Tire tubes of this general nature are principally used for the purpose of preventing sudden blow-outs, as for instance, when the shell or shoe breaks and the rubber wall of the inner tube explodes. Many accidents have occurred in this way. The use of inner chambers within the rubber wall tube or inner tubes within the same have aided materially in preventing the sudden escape of air from the tube and the danger occasioned by sudden blow-outs.

In one of the methods commonly employed, a so-called non-stretchable partition forms an air chamber away from the tread upon which the machine rides, so that when a blow-out occurs usually the non-stretchable partition -is not pierced and this retains the air within it in spite of the blow-out for sometime, thus preventing a sudden unbalance of the machine while it is in motion.

One of the difficulties in construction of this type is that the inner partition of its very nature cannot be made as strong as the outer shoe and yet it is placed under the same terrific strain when blow-outs occur or when any break occurs, as for instance as is common in air-craft tires in poor landings where often the outer shoe breaks or gives way. In order to take up such terrific strain which may occur, it is preferable to permit the so-called non-stretchable partition to have some stretch, both in its peripheral dimensions about the wheel and in its lateral dimensions in sectional elements of the shoe.

The applicant has learned in the present invention upon careful study and experiments that even with these precautions, when a blow-out occurs, the inner chamber does not stand up well under the strain. Frequently the valve is ripped out from its hole in the rim of the wheel and the portion of the expansible rubber tube which rests against the rim is entirely torn away from it. The applicant has found that the valve is usually drawn inwardly through the hole in the rim because of the release of pressure within the tube when it fails. In this case, the ordinary partition in the tube does not remain in place but is, rather, forced outward from the rim, pulling the sides of the expansible tube in the base with it to such a point Where the wall of the tube no longer furnishes a support. At this point the chamber which normally is supported by the rim of the wheel no longer has this support and the expansible portions of the inner tube are free to exp in the area where atmospheric pressure already exists. The base chamber, therefore, breaks.

The aim of the present invention is to overcome these difiiculties by providing a construc- 5 tion in which, after a break occurs, the base chamber at the rim which serves to lock the shoe upon the wheel, remains sufiiciently supported so that it not only serves to prevent the entire collapse or escape of the air within the tube, but also to retain the rubber in the base against the rim of the wheel so that it cannot be exposed through the movement and expansion of the separating element between the two chambers formed within the tube.

The present invention also has the advantage that it retains the shoe upon the rim of the machine. This permits the rubber in the shoe to be usefully applied as a riding cushion and prevent twisting and cutting, as often occurs, when a machine has to ride upon a fiat tire.

In the present invention special means'are used for retaining the flexible partition in relatively the same place near the rim of the wheel. In this connection the present invention is an improvement in the device shown and described in my copending application, Serial No. 430,595, filed February 12, 1942.

The same system for valve inflation may be used in the means in this invention as in the prior copending application.

Further merits and advantages of the present invention over the prior art will be more clearly understood from the description in the rest of the specification when taken in connection with the drawing in which Figure 1 shows a central fragmentary section taken through the tire and rim in the region of the inflating valves and Figures 2 and 3 show enlargements of details.

In the figures, the usual shoe or outer shell of the tire is indicated by 2, which has its base or beads I and l resting on the rim 3 or the vehicle, which as indicated in the figures is of the drop rim type, but any other type of rim may be used equally as well.

Within the shoe 2, when the shoe is inflated and on the wheel, is an inner tube 4, which may be of the usual type filling out the shoe and extending all around its inner surface and into the base or well 5 of the rim. Within the inner tube 4 there is provided a complete tube of substantially non-stretchable material 6. This tube is positioned within the tube 4 well within the arc struck from the center of the well 5 from one tip 1 of the rim to the other tip 8 of the rim. While the tube 6 is substantially non-stretchable as compared with the rubber tube 4, nevertheless it does stretch with the application of pressure in a manner as will be explained more fully later in another part of the specification.

The tube 6 has its side wall elements 9 and i securely attached to and sealed to the inner walls of the inner tube 4. This may be done in any of the usual ways as for instance by bufii ng the wall of the inner tube 4 and cementing the side walls 9 and IQ of the tube 6 to the buffed walls of the inner tube 4. The tube 6 is provided with a one way valve H by means of which the chamber l 2 within the tube may be inflated from the chamber I 3 within the inner tube 4. tube 6 i provided with air vents 2| and 22 positioned in the lower wall 24 of the, tube 6 so as to permit air to freely circulate to the place, or chamber 23 which is shut off by means of the tube 6 from the chamber I3. The chambers I2 and 23 however are at the same pressure since air can freely pass from one to the other. The inner portion. 24.. of. the tube. 6-: may dip down slightly into the well of the rim.

The valve may. be provided with a spring l4 exerting a slightpressure to. keep the valve ll closed. The chamber l.3.is inflated through the air conducting tube l.5..sealed between the tube 6. in its-side wall Hlxandv the wall of the inner tube 4. Thisair conducting tube l5 extends upward from thevalve Iii which passes-through an opening in the rim 3. and: is. sealed in the rubber wall of. the inner tube 4.

The valve It. does not. ordinarily permit air to enter directly into. thechamber 23 or the chamher I 2, since the end of the valve is sealed by means. of the air plug II. which normally is set uptightly. so that no airv willcome into or escape from v the chamber. l2, bymeans of the valve Hi. When it is. desired: to deflate the chamber 12 and thechamber 23, the stem of the valve 16 may be removed and a proper tool inserted'through it to loosen the air plug. so as to permit air in the chambers 23 and. I2 to escape through the plug opening l8. The inside wall-of the inner. tube 4 beyond. theregion in which the side walls 9- and [0.1 ofthe tube 6. arejoined to it may be covered.

with a self sealing com-pound 20 which under or dinary circumstances will serve theusual purpose ofsealing punctures which may occur through the rubber of the inner tube 4.

The tube 6 is of such a construction that the top. section 25.and thesidesectionsil and. I2 may stretch to areasonable extent. For this purpose these parts of'the tube may be constructed of rubberized fabric built up in layers in such a way that the fabric is biased to permit both peripheraland-lateral expansion of the tube in these sections of itsfabric. section 25 has itsthreads running diagonally to theplane of the wheel, this fabric will stretch both inthe plane of the wheel and laterally thereto and similarly the side portion of the tubes 9 and ID, will stretch in substantially the same manner. A stretch of perhaps 10% to maybe permissible in these portions, although it is preferable to confine the stretch to less than this amount between a condition where the chamber 13; has the. proper air pressure to the condition whichoccurs in a blow-out.

It should be notedthat when a blow-out occurs, the wall; portions 9, I0 and of the tube 6 will. be under increased strain clue to the fact that these portions must necessarily hold the air within the chambers I2 and 23 when the air in the chamber i3-has escaped. In this case how- The.

For. instance if the fabric in the ever the lower portion of the tube 24 has no increased strain placed upon it from the air within the chamber l2, since the chamber 23 is still inflated at the same pressure as the chamber I2. The sections of the tube 24 however acts as an anchor and pulls back the lower ends of the walls 9 and IQ all, around the periphery of-the wheel. To secure the section 24 even more permanently in this position, this portion of the tube should be made with its fabric not laid on the bias with respect to the tube, but rather the threads should run substantially in the direction of the plane of the wheel and laterally to it and this section may be thicker. than the top section 25. This may be accomplished by overlapping the fabrics in the base, of the inner tube to provide a thicker nonstretchable, portion on the inner side of the tube than on. the, outer side, these overlapping fabrics having thread running substantially in the plane of the; wheel and transverse thereto. The fabric for this purpose may be a woven fabric if desired, with the weft and woof at rightangles to each other. If therefore the weftof thefabric is substantially parallel to vertical planes through the wheel and the woof is at right angles to these planes, then the only stretch of the fabric will occur in the stretch of the threads which may be made very small. This construction will act to maintain the lower portions of the walls 9 and H1 in their position and will therefore tend to maintain the lower portions of the wall 4- in its original position, thus preventing the rubber from rising when a blow-out occurs. The lower portion 26 of the rubber tube 4 cannot be forced upward therefore between the tube 6 and the shoe, and it therefore will have rigid walls on all sides to retain it at all times in the same place. The only stretch on the section 24 in the tube 6 will be the endwise pull on this section by the sec tions 9 and I0, andthis will be offset by properly strengthening thepartition 24. A goodeffect however willalso. be gained if the partition 24 is of the same character. as the rest of the portions of the. tube Ii;

In addition to the advantages herein set forth, the same advantages will also be retained in this construction asin that of: my copending application mentioned. above.

In the expression in the claims of the present application, the inner tube 6 is referred to as havingan inner side and an outer side, the outer side in this. case. is the section of the tube that has the, larger peripheral circumference, whereas the inner sideis. the ection that has the smaller peripheral circumference.

Having now described my. invention, I claim:

I. In combination with the rim of the wheel having a central: well; and with a, neumatic tire casing having beads with clamping surfaces facing the rim of the wheel on which the casingfits,

an expansible inner tube adapted to be. inflated to fill out the innerspace of-the, casing, asuhstantiall non-expansible flexible tube positioned:

in the base. of the, inner tube andpartitioning said inner tube off intwo. sections, one section;

comprising a larger portionof the inner tube extending to the tread QfHthe, casing and the other portion comprising a, smaller chamber extendmg well within the arc struck from the center of thewell; as a center across from, one rim. tip.

to the other, said non-expansible tube having a base portion curved radially inward in the base and having therein, free air ventsto the. portion, of the inner. tube ppsitioned in, the baseof rimth e side walls ofsaid non-expansible, flex-,-

ible tube being joined to the side walls of said expansible inner tube.

2. In combination with the rim of a wheel and with a pneumatic tire casing having beads with clamping surfaces facing the rim of the wheel on which the casing fits, an expansible inner tube adapted to be inflated to fill out the inner space of the casing, a substantially non-expansible flexible tube having a top section extending across the inner tube from a point near the level of the rim edge from one side to the other side and having side walls joined to the side walls of the expansible tube adjacent the section of the tire casing which abuts against the rim of the wheel said non expansible flexible tube having a bottom section with a base portion curved radially inward in the base, said non-expansible tube partitioning by means of the top section of the non expansible tube said inner tube into two chambers, one of said chambers being formed by the space within said non-expansible tube and the space closed off by the non-expansible tube and the section of the expansible inner tube adjacent the rim of the wheel, said non-expansible tube having an air connecting passage to the space within the inner tube adjacent the rim of the wheel.

3. In combination with the rim of a wheel and with a pneumatic tire casing having beads with clamping surfaces facing the rim of the wheel on which the casing fits, an expansible inner tube adapted to be inflated to fill out the inner space of the casing, a substantially non-expansible flexible tube having a top section extending across the inner tube from a point near the level of the rim edge from one side to the other side and having side walls adhered to the side walls of the inner tube in sections of the casing adja-cent the rim of the wheel said non expansible flexible tube having a bottom section with a base portion curved radially inward in the base, said non-expansible tube partitioning by means of the top section of the non expansible tube, said inner tube into two chambers, the base section of the non expansible tube having a free communicating passage with the space within the inner tube adjacent the rim of the wheel, the section of said non-expansible tube on the inner side being of substantially less stretchable material than the portion of the tube on its outer side.

4. In combination with the rim of a wheel and with a pneumatic tire casing having beads with clamping surfaces facing the rim of the wheel on which the casing fits, an expansible inner tube adapted to be inflated to fill out the inner space of the casing, a substantially non-expansible flexible tube having a top section extending across the inner tube from a point near the level of the rim edge from one side to the other side and having side walls adhered to th side walls of the inner tube in sections of the casing adjacent the rim of the wheel said non-expansible flexible tube having a bottom section with a base portion curved radially inward in the base, said non-expansible tube partitioning by means of the top section of the non-expansible tube, said inner tube into two chambers, the base section of the non-expansible tube having a free communicating passage with the space within the inner tube adjacent the rim of the Wheel, the section of said non-expansible tube on the base section being made of fabrics lapped over one another to provide a thicker non-stretchable portion on the inner side of the tube than on the outer side thereof.

5. In combination with the rim of a wheel and casing having beads with clamping surfaces facing the rim of the wheel on which the casing fits, an expansible inner tube adapted to be inflated to fill out the inner space of the casing, a substantially non-expansible flexible tube having atop section extending across the inner tube from a point near the level of the rim edge from one side to the other side and having side walls adhered to the side walls of the inner tube in sections of the casing adjacent the rim of the wheel said non-expansible flexible tube having a bottom section with a base portion curved radially inward in the base, said non-expansible tube partitioning by means of the top section of the non-expansible tube, said inner tube into two chambers, the base section of the non-expansible tube having a free communicating passage with the space within the inner tube adjacent the rim of the wheel, the section of said non-expansible tube on the base section being made of fabrics lapped over one another to provide a thicker non-stretchable portion on the inner side of the tube than on the outer side thereof, the section of said non-expansible tube on the inner side being made of fabrics having their threads substantially in the plane of the wheel and transverse thereto, while the outer sections of said tube having fabric laid on a bias whereby the inner section of the tube is less expansible than the outer section thereof.

BERNARD E. MENDELSO-HN. 

